Internal combustion engines of the type in question are sufficiently well known and are already being employed in many forms in motor vehicle construction. To be able to enhance the performance of the pistons and hence also of the internal combustion engine in this context, the pistons are additionally cooled in regions subject to high thermal stress, e.g. in a combustion chamber recess and/or on a fire land, for which purpose a circumferential cooling channel is generally arranged in the piston head. Arranged in this cooling channel is a cooling medium, which brings about improved heat transfer from the combustion chamber recess or the fire land to cooler regions on a lower side of the piston. In the case of open cooling channels, cooling oil is generally sprayed into said channels. In this case, a cooling channel of this kind has at least one cooling oil inlet and at least one cooling oil outlet, through which the cooling oil is fed to the cooling channel and discharged therefrom. In the case of one-piece pistons, the cooling channel is often formed with an additional cooling channel cover attached afterwards. These cooling channel covers, which are shaped as sheet-metal rings for example, are sufficiently well known from the prior art.
DE 40 39 754 A1 discloses a piston of the type in question for an internal combustion engine, which has a sheet-metal ring for covering an annular cavity for receiving a cooling oil. On the one hand, the collar of the sheet-metal ring rests in a recess in an annular wall and, on the other hand, the sheet-metal ring is supported on a boss bush under preload by means of a holding strap. In order to increase piston pin lubrication at the same time as achieving improved piston cooling, beads are arranged on the sheet-metal ring in order to guide some of the cooling oil onto the piston pin boss. The disadvantage here is that the cooling oil does not impinge selectively on the piston pin boss but instead drips off in an uncontrolled manner and, as a result, efficient piston pin lubrication is impossible.
In order to achieve selective piston pin lubrication, “lubricating bores” leading in the direction of the piston pin from the cooling channel are often introduced, or cooling oil discharge bores leading in the direction of the piston pin boss are provided. For example, WO 2007/076811 A2 discloses a piston for an internal combustion engine which, in addition to an annular cooling channel in the piston head, has at least one oil feed bore and at least one oil discharge bore, each of which is aligned in the direction of the piston pin boss for the sake of cooling the latter. The disadvantage with such bores is that they have to be introduced subsequently by means of an additional work step, thereby increasing production costs.